Improvement in low-water detecters



Urrn STATES PATENT OFFICE'.

JOHN ASHOROFT, OF BROOKLYN, NEW YORK.

Speciilcation forming part of Letters Patent No. 55,221, dated June 5, 1866.

To all whom fit may concor/n:

Be it known that I, JOHN ASHGROFT, of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Low Water Detecters for Steam-Boilers; and I do hereby declare that the following is a full, clear, and exact description of the same.

My invention relates to that class of lowwater detecters in which steam takes the place of water in apparatus above the water-level of the boiler when the water-level in the boiler sinks too low. It reduces the number of joints in such apparatus and reduces the risk of leakage and derangement and makes such apparatus more certainly reliable.

By means of my invention I can render it impossible for the engineer to shut off the communication between the boiler and the part which gives the alarm. l

I will proceed to give what I consider the best mode of carrying out my invention, and will afterward designate the points which I believe to be new.

The accompanying drawing forms a part of this specilication, and represents the novel parts with so much of the ordinary parts as is necessary to understand their relation thereto.

Referring to the letters of reference on the drawing, A is a spherical cast-iron air-chamber, the same as is now in use inlow-water detecters except the lower part, which is made in theform as shown for the purpose of using my improved valve. B is a brass bushing, which holds the fusible plug C securely in its place. O is a fusible plug, which melts at the temperature of boiling water. D is a valve, provided with a screw on its stem for the purpose of closing the opening E. F is a spindle on the end of the valve D, which, being in contact with the fusible plug O, prevents the valve D from being screwed to its seat and until the fusible plug O is melted. G is a pipe, about six feet long, connected to the boiler, the lower end of which is open and stands below the proper water-level and at a point distant above the fines in the boiler established to give the low-water alarm.

The operation of the instrument is as follows, viz: Water being in the boiler, at its proper f level, covers thelower end of the tube Gr. When Y steam is generated the pressure in the boiler causes the water to rise in the pipe G, filling the pipe and partially lling the air-chamber A. So long as the water in the boiler remains above the lower end of the pipe G- the fusible plug O, being subject to a low temperature, remains unaffected. Should the water in the boiler fall below the end of the pipe G, the water is instantly displaced and its place supplied by hot steam, which, coming in contact with the fusible plug C, immediately melts or dissolves it, letting the steam escape through the passage H, from which is a branch (not represented) to which is connected an alarm steam-whistle, which is blown by the escaping steam.

Some of the advantages due to certain features of my improvement may be separately enumerated, as follows: First, by reason of the fact that the screw-valve D is employed in the place represented in lieu of the plug-cock heretofore employed at a lower level, I am able to reduce the number of joints by dispensing with the two joints heretofore employed, one above and onle below the plug-cock, am able to avoid the risk of leakage due to the employment of a plug-cock, and am able more cheaply and conveniently to introduce the addition which constitutes the second feature; second, by reason of the fact that the extension F goes in contact with the plug or disk O, so as to prevent the closing oif of the steam until after the disk G has melted, l am able to insure that the steam shall not be shut off under any circumstances, either by accident or design, until the fusible portion O has melted and the alarm has been given. y

It will be .observed that the hollow thimble B and the boss into which its screws are sufficiently long to allow a new fusible disk to be introduced and screwed partly home while the valve D is closed. This allows me to apply a new disk, when necessary, while steam is on the boiler. After the valve D is opened it is easy to force the previously introduced disk O with the boiler below the proper waterlne, ble part cannot be closed untilafter the fusithe discharge-passage H, und the fusible disk ble part has yielded to the temperature, as G with the screw-valve D, arranged substanherein speoied.

tiztlly as and for the purpose herein set forth.

. `1 2. The beari 11g-piece F, in combination with JOHN ASHLROFT' the fusible disk C and the connections Gr and Witnesses H, arranged as specified, so that the eommu- THOMAS D. STETSON,

nieation between the boiler and the said fusi- W. K. THOMAS. 

